JP5265668B2 - Estimating thermal noise and thermal rise in wireless communication systems - Google Patents

Description

Claiming priority under 35 USC § 119

  This application was filed on April 24, 2007 and is entitled “Method of Estimating Rise-over-Thermal, RoT”, US Provisional Application No. 60/913, Claims priority to 778, which is assigned to the assignee of the present application and is hereby expressly incorporated by reference.

Field

  The present disclosure relates generally to communication, and more particularly to techniques for estimating thermal noise and thermal rise (RoT) in wireless communication systems.

background

  Wireless communication systems are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and so on. Such a system may be a multiple access system that can support multiple users by sharing available system resources. Examples of such multiple access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal FDMA (OFDMA) systems, and single carrier FDMA ( SC-FDMA) system.

  In a CDMA communication system, multiple user equipments (UEs) may currently transmit to the Node B on the uplink. Transmissions from each UE act as interference to transmissions from other UEs at Node B. The received signal quality of a given UE depends on various factors such as the amount of transmit power used by the UE, the path loss from the UE to the Node B, the amount of interference observed by the UE at the Node B Yes. When the UE increases their transmit power and / or when more UEs are added, the total interference at the Node B increases. At some point, the UE cannot further increase their transmit power and cannot add any more UEs. Thus, system capacity is limited by interference on the uplink.

  RoT is the ratio of total noise and interference to thermal noise in the cell. RoT is a basic measure of load on the uplink. In order to avoid system instability, it would be desirable to accurately estimate RoT so as to keep the uplink load below the target level.

Overview

  A technique for estimating thermal noise and RoT in a communication system will now be described. In one aspect, thermal noise may be estimated in the sideband between adjacent frequency channels. It may be assumed that the thermal noise density is constant over frequency. The thermal noise density in the sideband may be measured and used as an estimate of the thermal noise density in the signal band.

  In one design, the received power in the sideband may be measured, eg, converting a block of samples to the frequency domain to obtain a block of transform coefficients, and then transform coefficients in the sideband To obtain the received power in the sideband. Thermal noise may be estimated based on the received power measured in the sideband (eg, by filtering it). For example, the received power in the signal band is also measured by filtering each block of transform coefficients with a matched filter and calculating the total power of the filtered coefficients in the signal band, and receiving in the signal band Electric power may be acquired. Based on the received power measured in the signal band (eg, by filtering it), the total received power may be estimated. Next, RoT may be estimated based on the estimated thermal noise and the estimated total received power.

  In one design, the available load for the cell may be estimated based on the estimated RoT. Scheduling and / or admission control may be performed based on the available load. In one design, users to be admitted or scheduled may be selected, the selected user's load may be determined, and the available load may be updated based on the selected user's load. .

  Various aspects and features of the disclosure are described in further detail below.

FIG. 1 shows a wireless communication system. FIG. 2 shows a graph of normalized cell throughput versus RoT on the uplink. FIG. 3 shows multiple CDMA channels in the frequency band. FIG. 4 shows a receiver that can estimate thermal noise and RoT. FIG. 5A shows down-conversion and sampling of a radio frequency (RF) signal. FIG. 5B shows the digitized signal from the analog to digital converter (ADC). FIG. 6 shows a process for estimating thermal noise and RoT. FIG. 7 shows a block diagram of the Node B and the UE.

Detailed description

  The techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA systems. The terms “system” and “network” are often used interchangeably. A CDMA system may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, and so on. UTRA includes wideband CDMA (WCDMA) and other CDMA variants. cdma2000 covers IS-2000, IS-95, and IS-856 standards. A TDMA system may implement a radio technology such as Global System for Mobile Communications (GSM). The OFDMA system is a wireless technology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.20, IEEE 802.16 (WiMAX), IEEE 802.11 (WiFi), Flash OFDM (registered trademark), etc. May be realized. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Development (LTE) is an upcoming release of UMTS that utilizes E-UTRA. UTRA, E-UTRA, UMTS, LTE, and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2).

  For clarity, certain aspects of the technology are described below with respect to UMTS, and UMTS terminology is used in much of the description below. The term “CDMA” generally refers to any CDMA variant (eg, WCDMA, cdma2000), and the term “WCDMA” refers to a particular variant of CDMA as defined by 3GPP.

  FIG. 1 shows a wireless communication system 100, which may be a Universal Terrestrial Radio Access Network (UTRAN) in UMTS. System 100 includes a plurality of Node Bs 110. The Node B is a fixed station that communicates with the UE, and may be referred to as an evolved Node B (eNB), a base station, an access point, or the like. Each Node B 110 provides communication coverage for a particular geographic area 102 and supports communication for UEs located within the coverage area. The Node B coverage area may be divided into multiple (eg, three) smaller areas, each smaller area being served by a respective Node B subsystem. The term “cell” may refer to the smallest coverage area of Node B and / or the Node B subsystem responsible for this coverage area, depending on the context in which the term is used. In some systems, the term “sector” may refer to the smallest coverage area of a base station and / or base station subsystem that is responsible for this coverage area. For clarity, the cell concept in UMTS is used in the following description.

  Network controller 130 may be coupled to Node Bs 110 and provides coordination and control for these Node Bs. The network controller 130 may be a single network entity or a collection of network entities. For example, the network control device 130 may be a radio network control device (RNC) in UMTS.

  UE 120 may be spread throughout the system, and each UE may be stationary or mobile. A UE may also be referred to as a mobile station, terminal, access terminal, mobile device, subscriber unit, station, etc. The UE may be a cellular phone, a personal digital assistant (PDA), a wireless communication device, a handheld device, a wireless modem, a laptop computer, and so on. The UE may communicate with Node B via transmission on the downlink and uplink. The downlink (ie, forward link) refers to the communication link from the Node B to the UE, and the uplink (ie, reverse link) refers to the communication link from the UE to the Node B. For clarity, FIG. 1 shows only uplink transmissions from UE 120 to Node B 110. In FIG. 1, a solid line with a single arrow indicates transmission to the serving cell, and a broken line with a single arrow indicates transmission to a non-serving cell. The terms “UE” and “user” are used interchangeably herein.

  As shown in FIG. 1, each cell may receive transmissions from users not served by that cell as well as transmissions from users served by that cell. The total interference observed in each cell consists of (1) intra-cell interference from users in that cell and (2) inter-cell interference from users in other cells. As described below, intra-cell interference and inter-cell interference may have a significant impact on performance and may be taken into account when scheduling users.

  On the uplink in system 100, transmissions from each user act as interference to transmissions from other users in the serving cell. Thus, whenever a new user is scheduled on the uplink, transmissions from this user will increase interference to other users. The amount of interference caused by a new user depends on various factors such as the amount of transmit power used by the user, the path loss from user to cell, and so on. As users are added, other active users may need to increase their transmit power and total interference in the cell may increase. At some point, it may not be possible to add any more users because the system is interference limited on the uplink.

  FIG. 2 shows a graph of normalized cell throughput versus RoT for uplink. The normalized cell throughput is the total throughput of all users on the uplink divided by the maximum total throughput. As shown in FIG. 2, cell throughput increases at a higher rate at lower RoT and asymptotically reaches a maximum at higher RoT.

It may be desirable to accurately estimate / measure RoT in a cell. The estimated RoT may be used to admit and / or schedule users in the cell and ensure that the cell operates at the target RoT. The RoT of the cell may be expressed as follows:

Where I ₀ is the total noise and interference observed by the cell,
N ₀ is the thermal noise observed by the cell.

As shown in Equation (1), an accurate estimate of RoT may be obtained along with an accurate estimate of I _{0 and} an accurate estimate of N ₀ . As described below, the total noise and interference I ₀ may be estimated based on the total power received at the cell. The thermal noise N ₀ may be estimated during no signal intervals where no user transmits on the uplink. N ₀ may then be estimated based on the total received power at the cell during the no signal interval. However, such no-signal intervals may not be available in some systems. For example, in an asynchronous system where the timing of each cell may be asynchronous with the timing of other cells, it may be difficult to obtain a no signal interval.

In one aspect, the thermal noise N ₀ may be estimated in the sideband between adjacent CDMA channels. Sidebands may also be referred to as guard bands, stopbands, etc. The thermal noise density may be assumed to be constant across a single band and sidebands. Next, the thermal noise density in the sideband may be measured and used as an estimate of the thermal noise density in the sideband.

FIG. 3 shows an example of M CDMA signals on M CDMA channels in a frequency band, where M may be any integer value. A CDMA channel may also be referred to as a UMTS channel, frequency channel, carrier, etc. The M CDMA signals may be centered on f _ch1 to f _chM frequencies, which may be selected by the network operator. Each CDMA signal has only one band, f _BW , and may be determined based on the chip rate used by the system. Adjacent CDMA channels may be _freed by f _sp , where typically f _sp > 2f _BW . For WCDMA, the chip rate is 3.84 megachips per second (Mcps), and the WCDMA signal has a band on both sides, 2f _BW = 3.84. The spacing between adjacent WCDMA channels may typically be 5.0 MHz, but may be close to 4.8 MHz.

  The WCDMA signal is required to have an output power that conforms to the spectral output mask. The spectral output mask requires the WCDMA signal level to drop from the carrier frequency by at least 35 decibels (dB) at a 2.5 MHz offset and to drop by more than 35 dB at a larger frequency offset. The output request for WCDMA is entitled “User Equipment (UE) Radio Transmission / Reception (FDD)” and is provided in publicly available 3GPP TS 25.101.

  FIG. 4 shows a block diagram of a design of a receiver 400 that can estimate thermal noise and RoT. Receiver 400 may be part of a Node B or some other entity. Within receiver 400, antenna 412 receives uplink signals from the UE and provides received RF signals to RF front end unit 414. Within the RF front end unit 414, the received RF signal may be amplified by a low noise amplifier (LNA), filtered by a bandpass filter, or downconverted by a mixer. In one design, the RF front end unit 414 provides a downconverted signal that includes a desired CDMA signal at or near DC. In another design, the RF front end unit 414 provides a down-converted signal that includes the desired CDMA signal at the intermediate frequency (IF). In general, the desired CDMA signal may be downconverted to any frequency that is suitable for subsequent processing.

  An amplifier (Amp) 416 amplifies the downconverted signal from the RF front end unit 414 with a gain of G and provides an amplified and downconverted signal. The gain G may be selected such that the thermal noise floor of the amplified signal is higher than the quantization noise of the subsequent ADC 418.

The ADC 418 digitizes the amplified, downconverted signal and provides samples at a sampling rate of f _samp , where typically f _samp > 2f _BW . The ADC 418 may oversample the desired CDMA signal, which may be at or near DC. The ADC 418 may also undersample the desired CDMA signal, which may be at IF and may be aliased to a lower frequency by undersampling. In either case, the sample contains the desired CDMA signal in the frequency range of 0 to f _samp .

FIG. 5A shows a down-conversion and IF sampling design by receiver 400. The received RF signal provided to the RF front end unit 414 includes the desired CDMA signal centered at the frequency of f _ch . In this design, RF front-end unit 414, provides the received RF signal may be down-converted from RF to IF, the center frequency of f _IF, including the desired CDMA signal, a downconverted signal May be. The ADC 418 may digitize the downconverted signal at a sampling rate of f _samp . The desired CDMA signal may be undersampled so that the image of the desired CDMA signal is then at frequencies of + − (f _IF −f _samp ) and + − (f _samp −f _IF ). It may result in appearing. For example, the IF frequency may be f _IF = 70 MHz, the sampling rate may be f _samp = 16 chip rate, or 61.44 megasamples per second (Msps), and the CDMA signal image May be + -8.56 MHz and + -52.88 MHz.

FIG. 5B shows a diagram of the digitized signal from ADC 418 according to one design. In this design, the digitized signal is centered on the frequency of f _c, containing the desired CDMA signal. Center frequency f _c is a down-converted by the RF front-end unit 414, rely on the sampling rate of the ADC 418. The signal band of the CDMA signal has a width of 2f _sig , and is a frequency f _c + f _sig from the frequency f _c −f _sig . The signal band f _sig on one side may be less than the band f _BW on one side of the CDMA signal, may be equal to f _BW , may be greater than f _BW , and may be selected based on signal characteristics. In one design, the signal band 2f _sig may be selected as a band that captures a predetermined percentage (eg, 99%) of the total received power after matched filtering.

As shown in FIGS. 5A and 5B, when the center frequency is not DC, the sideband includes a right sideband portion (ie, right side) and a left sideband portion (ie, left side). Good. The right sideband portion has a width of f _side and is from the frequency f _c + f _sig to the frequency f _c + f _sig + f _side . The left sideband portion has a width of f _side and is from the frequency f _c -f _sig to the frequency f _c -f _sig -f _side . The width of each sideband portion may be selected based on the spacing between the CDMA channel and / or other coefficients.

In the design shown in FIG. 5B, the CDMA signal is centered on a positive frequency. In another design, the CDMA signal is centered around DC or f _c = 0 Hz. In this design, the signal band may be a f _sig from DC, the sideband may be f _sig + f _side from f _sig. The signal band and sideband may also cover other frequency ranges.

  Referring back to FIG. 4, even if ADC 418 is selected such that its quantization noise is below the thermal noise floor and that its dynamic range is sufficient for the largest expected received signal. Good. In one design, the ADC 418 has 32 target variables when the receiver input is removed, which corresponds to the 5 bits being used for quantization. In one design, a dynamic range of 13 dB or more may be handled with four or more additional bits. In this way, the ADC 418 may have 9 or more bits. Other bit widths may also be used for the ADC 418.

  A fast Fourier transform (FFT) unit 420 divides the sample from the ADC 418 into blocks. In one design, each block contains N consecutive samples and the blocks do not overlap. In another design, the blocks overlap and each block contains a new sample along with some samples from the previous block. In any case, N may be a power of 2 and may be equal to 8192 or some other value. The FFT unit 420 performs an N-point FFT on the N samples of each block and provides N transform coefficients for the corresponding block to the first processing path 430 and the second processing path 440. . The path 430 calculates the total received power in the signal band. Path 440 calculates thermal noise in the sideband.

Within the first processing path 430, the matched filter 432 filters the N transform coefficients for each block and provides the N filtered coefficients for the corresponding block. The matched filter 432 may be the same matched filter used in the data path for processing the uplink signal from the user. The power calculation unit 434 calculates the total power in the signal band for each block as follows.

Where Y _m (k) is a transform coefficient for frequency bin k in block m,
H (k) is the gain of the matched filter 432 with respect to frequency bin k,
P _sig (m) is the signal band power for block m.

In Equation (2), Y _m (k) · H (k) is a filtered coefficient for the frequency bin k from the matched filter 432. Equation (2) sums the square magnitudes of the filtered coefficients within the signal band from f _c −f _sig to f _c + f _sig to obtain the signal band power for the block.

In one design, filter 436 filters the signal band power with an infinite impulse response (IIR) filter as follows.

Where α _sig is the IIR coefficient that determines the amount of averaging,
P~ _sig (m) is the signal band power filtered for block m.

The IIR coefficient α _sig may be selected based on a desired amount of averaging over the signal band power. In one design, each block covers 0.2 slots in WCDMA, ie, 0.133 milliseconds (ms), and the IIR coefficient is selected as α _sig = 1/128, for a time of approximately 25 slots. A constant may be acquired. Other values may be used for the IIR coefficient. Filtering may also be performed with a finite impulse response (FIR) filter, a moving average filter, or the like. In any case, the filter 436 provides the filtered signal band power for each block as the total received power to the RoT calculation unit 450.

  Within the second processing path 440, the sideband band selector 442 receives N transform coefficients in each block, provides the transform coefficients within the sideband, and discards the remaining transform coefficients. To do. A matched filter is not included in the second processing path 440 so that thermal noise outside the signal band is not attenuated.

In one design, power calculation unit 444 calculates the total power in the sideband for each block as follows:

Here, P _side (m) is the sideband power for the block m.

In Equation (4), the sum of the left from f _c -f _sig -f _side of f _c -f _sig +1, summing the squared magnitude of the transform coefficients in sideband portion of the left. Total right sums from f _c + f _sig +1 of _{f c + f sig + f side} , the square magnitude of the transform coefficients of the side wave band portion of the right. The sideband power is equal to the sum of the total power for the left and right sideband portions.

In one design, filter 446 filters the sideband power with an IIR filter as follows.

Where α _side is an IIR coefficient that determines the amount of averaging,
P to _side (m) is the filtered sideband power for block m.

The IIR coefficient α _side may be selected based on the desired amount of averaging over the sideband power. Since the thermal noise power changes more slowly than the signal power, α _side may be smaller than α _sig . In one design, α _side may be selected as follows.

When f _side << f _sig , α _side may be a very small value, and the IIR filter may be realized by calculation with sufficient accuracy.

In another design, the filter 446 calculates a moving average of sideband power over a length L window as follows.

The window length L may be selected as follows.

  Filter 446 may also filter sideband power with an FIR filter or in some other manner. In any case, the filter 446 provides the filtered sideband power for each block as thermal noise to the RoT calculation unit 450.

Unit 450 from filter 436, receives a total received power P～ _sig for each block (m), from the filter 446, the thermal noise P~ _side (m) for each block. In one design, unit 450 calculates RoT as follows:

Here, K _cal is a calibration coefficient, and f _{sig, eff} is an effective signal bandwidth of the matched filter 432.

The effective signal bandwidth may be expressed as follows:

Here, H (k) is assumed to be normalized so that the passband has a magnitude of 1.0.

In Equation (9), the total received power is divided by f _{sig, eff} to obtain the received power density, and the thermal noise power is divided by 2f _side to obtain the thermal noise density. In a similar sense, the thermal noise power P to _side (m) from the sideband may be scaled by the ratio f _{sig, eff} / 2f _side to obtain the thermal noise power for the signal band. In either case, scaling by f _{sig, eff} and 2f _side ensures that RoT is calculated using the same unit quantities in both the numerator and denominator. The calibration factor K _cal may be selected so that during calibration, RoT is normalized to 0 dB when no received signal is applied to the antenna input.

In one design, the sampling rate is 16 times the chip rate (ie, chipx16) and is given as f _samp = 16 × 3.84 = 61.44 MHz. On the sample from the ADC 418, an 8192-point FFT is performed and the frequency bin spacing is 7.5 KHz. The signal band is f _sig = 2.4 MHz, which corresponds to 320 frequency bins. The sideband is between 2.4 and 2.5 MHz, or f _side = 0.1 MHz, which corresponds to 13 frequency bins. The signal band and sideband may also be defined in other widths that are smaller or larger than the values given above. Desired CDMA signal is not the f _c, if centered at DC, and the signal band, the sideband may also be defined differently.

The estimated RoT from equation (9) may be used for scheduling, admission control, and / or other purposes, and the total cell load may be expressed as:

Where L _in-cell is the load of the user being served by the cell, and L _{ns, AS} is the load of the user not being served by the cell but having a cell in their active set, L _out is the load of users in other cells who do not have a cell in their active set, and L _total-cell is the total load of the cell. L _out corresponds to interference from users in other cells.

The total cell load may be expressed in terms of estimated RoT as follows:

The cell may estimate L _in-cell and L _{ns, AS} based on the uplink signal received from the user. The cell may calculate L _total-cell based on the estimated RoT and then calculate L _out based on L _in-cell , L _{ns, AS} and L _total-cell . _{Cell, L in-cell, L ns} , filter the _AS, and L _out, the corresponding filtered loads _{L~ in-cell, L~ ns,} AS, and • L ^ _out a may be acquired respectively .

The cell may calculate the target total load based on the target RoT as follows.

Where L _{total, target} is the target total load for the cell,
RoT_target is the target RoT for the cell.

The cell may calculate the available load on the cell as follows:

Here, _Lavail-cell is a load available for the cell.

The cell may admit new users or schedule users based on the available load. For a given user i who is being admitted or scheduled, the load by user i may be calculated as follows:

Where (E _c ) _i is the total energy per chip for user i,
(E _c / N _t ) _i is the ratio of total energy per chip to total noise for user i,
L _i is the load of user i.

The ratio of total energy per chip to total noise for user i may be expressed as:

Where E _cp is the energy per chip for the pilot,
E _c is the total energy per chip for data, overhead and pilot,
N _t is the total noise and interference observed by the cell,
(E _cp / N _t ) _i is the ratio of chips per pilot energy to total noise for user i,
O2P _i is the ratio of overhead to pilot for user i,
T2P _i is the ratio of traffic to pilot for user i.

(E _cp / N _t ) _i may be estimated based on the pilot transmitted by user i on the uplink. User i may transmit overhead or signaling at the power level determined by O2P _i and may transmit data at the power level determined by T2P _i . O2P _i is a ratio of the signaling power level to the pilot power level, and may be a fixed value. T2P _i is the ratio of data power level to pilot power level and may depend on the data rate assigned to user i. The pilot power level may be adjusted via power control to achieve a desired level of performance, eg, target block error rate (BLER). The ratios O2P _i and T2P _i may be known or determined for user i. For user _{i (E c / N t)} i is the estimated _{(E cp / N t) i} , and may be calculated based on the known O2P _i and T2P _i.

The available load on the cell may be updated to reflect user i's admission or scheduling as follows.

  In a similar manner, additional users may be admitted and / or scheduled until all available loads for the cell are used. User scheduling based on available load is entitled “Scheduling Based on Rise to Heat in Wireless Communication Systems”, filed Feb. 14, 2008 and commonly assigned US patent application serial. This is described in detail in No. 12 / 031,245. Scheduling and admission control using estimated RoT may also be performed in other ways.

The techniques described herein provide certain advantages. An accurate estimate of thermal noise may provide an accurate estimate of RoT, which may allow for the derivation of a more accurate estimate of the outer load L _out , which instead of that _Allows the derivation of a more accurate estimate of the available load _{Lavail_cell} for the cell. A more accurate _{Lavail_cell} may _allow the cell to operate closer to the target total load L _{total, target} , which may improve capacity. A more accurate _{Lavail_cell} may also _allow the cell to operate at higher target loads while still ensuring stability.

  For clarity, certain aspects of techniques for estimating thermal noise and calculating RoT in CDMA systems have been described. In general, in any wireless communication system, wireline communication system, etc., this technique may be used to estimate thermal noise. Various metrics may be calculated using the estimated thermal noise. For example, the estimated thermal noise may be used to calculate interference-over-thermal (IoT) in an OFDMA or SC-FDMA system. An OFDMA or SC-FDMA system may include K total subcarriers, and a subset of the available K total subcarriers and the remaining subcarriers may serve as guard subcarriers and are not used. . (I) As described above, for received power in the sideband between carriers, (ii) received power of guard subcarriers, or (iii) for a frequency range not used for communication Thermal noise may be estimated based on the received power.

  FIG. 6 shows a design of a process 600 for estimating thermal noise and RoT in a communication system. Process 600 may be performed by a Node B or some other entity. Received power in a sideband outside the signal band may be measured (block 612). Sideband location may be selected based on frequency spacing between adjacent CDMA channels and / or other factors. In one design of block 612, the samples from the ADC may be divided into N sample blocks, with N samples of each block being transformed (eg, with an N-point FFT) to the corresponding block. N conversion coefficients may be acquired. The received power in the sideband may be obtained by calculating the total power of the conversion coefficient in the sideband. The received power in the sideband may be measured by other methods.

  Thermal noise may be estimated based on the received power measured in the sideband (block 614). In one design of block 614, the received power measured in the sideband may be filtered (eg, with an IIR filter or a moving average filter) to obtain estimated thermal noise.

  Received power may be measured in the signal band (block 616). In one design of block 616, the N transform coefficients for each block may be filtered with a matched filter to obtain the N filtered coefficients for the corresponding block. The total power of the filtered coefficients in the signal band may be calculated to obtain the received power in the signal band. The received power in the signal band may be measured by other methods.

  Based on the received power measured in the signal band, the total received power may be estimated (block 618). In one design of block 618, the measured received power in the signal band may be filtered (eg, with an IIR filter) and an estimated total received power may be obtained.

  RoT may be estimated based on the estimated thermal noise and the estimated total received power (block 620). In one design, RoT is calculated based on estimated thermal noise, estimated total received power, sidebands, effective signal bandwidth relative to total received power, and a calibration factor, eg, as shown in equation (9). May be. The calibration factor may be selected to provide a predetermined RoT value when no signal is applied.

  For example, as shown in equation (12), the available load for the cell may be estimated based on the estimated RoT (block 622). Scheduling and / or admission control may be performed based on the available cell load (block 624). In one design of block 624, for example, as shown in equation (15), a user to be admitted or scheduled may be selected and the load of the selected user may be determined. Next, for example, as shown in Equation (17), the available cell load may be updated based on the selected user load. The available cell load may be used for scheduling and / or admission control in other ways. Estimated thermal noise, estimated RoT, and / or other information may also be provided by the Node B to the network controller.

  FIG. 7 shows a block diagram of a design of Node B 110 and UE 120, which is one of Node Bs and one of UEs in system 100 of FIG. At UE 120, a transmit (TX) data processor 714 receives traffic data from data source 712 and controls information from controller / processor 720. A TX data processor 714 processes (eg, encodes and symbol maps) data and control information, performs modulation (eg, for CDMA), and provides output chips. A transmitter (TMTR) 716 conditions (eg, converts to analog, filters, amplifies, and upconverts) the output chip and generates an uplink signal, which is transmitted via antenna 718. .

  At Node B 110, antenna 752 receives uplink signals from UE 120 and other UEs and provides received RF signals to a receiver (RCVR) 754. A receiver 754 conditions and digitizes the received RF signal and provides samples. Receiver 754 may include RF front end unit 414, amplifier 416, and ADC 418 in FIG. A receive (RX) data processor 756 performs demodulation on the samples (eg, for CDMA), demodulates and decodes the resulting symbols, and obtains decoded data and control information. Processor 756 provides decoded data to data sink 758 and provides decoded control information to controller / processor 760. Processors 756 and / or 760 may include units 420-450 in FIG.

  On the downlink, TX data processor 774 at Node B 110 receives traffic data from data source 772 for the UE scheduled for transmission on the downlink and control information from controller / processor 760. Data and control information is processed (eg, encoded, symbol mapped, and modulated) by TX data processor 774 and further adjusted by transmitter 776 to generate a downlink signal, which is routed through antenna 752. Sent by. At UE 120, the downlink signal from Node B 110 is received by antenna 718, conditioned by receiver 732, and demodulated and decoded by RX data processor 734.

  Controllers / processors 720 and 760 direct the operation at UE 120 and Node B 110, respectively. Controller / processor 760 may perform or direct process 600 in FIG. 6 and / or other processes for the techniques described herein. Memories 722 and 762 store program codes and data for UE 120 and Node B 110, respectively. A scheduler 764 may schedule UEs for data transmission on the downlink and / or uplink and may allocate resources for the scheduled UEs. The scheduler 764 may perform scheduling using the estimated RoT described above.

  Those skilled in the art will appreciate that a variety of different techniques and techniques may be used to represent information and signals. For example, data, instructions, commands, information, signals, bits, symbols and chips referenced throughout the above description may be voltage, current, electromagnetic waves, magnetic or magnetic particles, optical or light particles, or any of these You may express by a combination.

  The various exemplary logic blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. Will be more accurately recognized by those skilled in the art. In order to clearly illustrate the interchangeability of hardware and software, various exemplary components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the particular application and design constraints imposed on the overall system. Those skilled in the art may vary the method for each particular application to implement the described functionality, but such implementation decisions are interpreted as causing deviations from the scope of the present invention. should not do.

  Various exemplary logical blocks, modules and circuits described in connection with the embodiments disclosed herein are general purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gates. Implemented in an array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or combinations thereof designed to perform the functions described herein, or May be implemented. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, state machine. The processor may also be implemented as a combination of computing devices, eg, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors with a DSP core, or some other such configuration. May be.

  The method or algorithm steps described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module resides in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or some other form of storage medium known in the art. It may be. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In alternative embodiments, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may be present in the user terminal. In an alternative embodiment, the processor and the storage medium may exist as discrete components in the user terminal.

  In one or more exemplary designs, the functions described may be implemented by hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code in a computer-readable medium or transmitted over a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer readable media can be RAM, ROM, EEPROM, CD-ROM, and other optical disks, magnetic disk storage or storage devices, or any desired Any other medium that can be used to carry or store the program code in the form of instructions or data structures and that can be accessed by a computer can be included. Also, any connection is strictly referred to as a computer readable medium. For example, software can use a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology such as infrared, wireless, or microwave from a website, server, or other remote source. When sent in use, coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology such as infrared, radio, microwave, etc. shall be included in the definition of the media. Discs (disk and disc), as used herein, are compact discs (CD), laser discs (registered trademark), optical discs, digital general purpose discs (DVD), floppy (registered trademark) discs, Blu-ray (registered trademark) A disk includes a disk, which normally reproduces data magnetically, and a disk reproduces data optically with a laser. Combinations of the above will also be included within the scope of computer-readable media.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit and scope of the invention. Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Hereinafter, the invention described in the scope of claims of the present application will be appended.
[1] In a method for estimating thermal noise in a communication system,
Measuring the received power in the sideband outside the signal band;
Estimating thermal noise based on received power measured in the sideband;
Including methods.
[2] Measuring the received power in the sideband is
Splitting the samples into blocks where each block contains N samples;
Transforming N samples of each block to obtain N transform coefficients of the corresponding block;
Calculating the total power of the conversion coefficient in the sideband and obtaining the received power measured in the sideband;
Wherein N is greater than 1, the method of [1] above.
[3] Estimating the thermal noise
The method according to [1], further comprising: filtering received power measured in the sideband to obtain estimated thermal noise.
[4] Estimating the thermal noise
The method according to [1], further comprising: filtering received power measured in the sideband with an infinite impulse response (IIR) filter to obtain estimated thermal noise.
[5] Estimating the thermal noise
The method according to [1], further comprising: averaging received power measured in the sideband over a sliding window having a predetermined length to obtain an estimated thermal noise.
[6] measuring received power in the signal band;
Estimating a total received power based on the received power measured in the signal band;
Estimating a rise against heat (Rise-over-Thermal, RoT) based on the estimated thermal noise and the estimated total received power;
The method of [1] above, further comprising:
[7] Measuring the received power in the signal band includes
Splitting the samples into blocks where each block contains N samples;
Transforming N samples of each block to obtain N transform coefficients of the corresponding block;
Calculating the total power of the transform coefficients in the signal band to obtain the received power measured in the signal band;
Wherein N is greater than 1, the method of [6] above.
[8] Measuring the received power in the signal band,
Filtering the N transform coefficients of each block with a matched filter to obtain N filtered coefficients of the corresponding block;
Calculating the total power of the filtered coefficients in the signal band to obtain the received power measured in the signal band;
The method of [7], further comprising:
[9] Estimating the total received power is:
The method according to [6], further comprising: filtering received power measured in the signal band to obtain the estimated total received power.
[10] Estimating the RoT
The method according to [6] above, further comprising calculating the RoT based on the estimated thermal noise, the estimated total received power, the sideband, and an effective signal band for the total received power.
[11] Estimating the RoT
The method of [10] above, further comprising calculating the RoT based further on a selected calibration factor so as to provide a predetermined RoT value when no signal is applied.
[12] estimating an available load for the cell based on the estimated RoT;
Performing scheduling and admission control based on the available load;
The method of [6] above, further comprising:
[13] Performing the scheduling and admission control includes
Selecting a user to admit or schedule;
Determining the load of the selected user;
Updating the available load based on the selected user load;
The method according to [12] above, comprising:
[14] amplifying the analog input signal to obtain an amplified signal having a thermal noise floor higher than the quantization noise of an analog-to-digital converter (ADC);
Digitizing the amplified signal with the ADC to obtain a sample;
Measuring received power in the sidebands based on the samples;
The method of [1] above, further comprising:
[15] The method of [6], further comprising reporting the estimated thermal noise, the estimated RoT, or both to a network controller.
[16] The method of [1] above, wherein a location of the sideband is selected based on frequency spacing between adjacent CDMA channels.
[17] The method of the above-mentioned [1], further comprising estimating interference-over-thermal (IoT) based on the estimated thermal noise.
[18] The method of [1] above, wherein the sideband includes guard subcarriers and the signal band includes usable subcarriers among a plurality of subcarriers.
[19] In an apparatus for wireless communication,
Measure the received power in the sideband outside the signal band,
Estimate thermal noise based on received power measured in the sideband
An apparatus comprising at least one processor.
[20] The at least one processor is:
Divide samples into blocks where each block contains N samples,
Transform N samples for each block to obtain N transform coefficients for the corresponding block;
Calculate the total power of the conversion coefficient in the sideband to obtain the received power measured in the sideband;
Here, the apparatus according to [19], wherein N is greater than 1.
[21] The at least one processor is:
[19] The apparatus according to [19], wherein the received power measured in the sideband is filtered to obtain estimated thermal noise.
[22] The at least one processor is:
Measuring the received power in the signal band;
Estimating the total received power based on the received power measured in the signal band;
[19] The apparatus according to [19], wherein a rise with respect to heat (RoT) is estimated based on the estimated thermal noise and the estimated total received power.
[23] The at least one processor is:
Divide samples into blocks where each block contains N samples,
Transform N samples for each block to obtain N transform coefficients for the corresponding block;
Calculating the total power of the transform coefficients in the signal band to obtain the received power measured in the signal band;
Here, the apparatus according to [22], wherein N is greater than 1.
[24] The at least one processor is:
Based on the estimated RoT, estimate the available load for the cell;
[22] The apparatus according to [22], wherein scheduling and admission control are executed based on the available load.
[25] In the device,
Means for measuring received power in a sideband outside the signal band;
Means for estimating thermal noise based on received power measured in the sideband;
A device comprising:
[26] The means for measuring the received power in the sideband is
Means for dividing the samples into blocks each containing N samples;
Means for transforming N samples of each block to obtain N transform coefficients of the corresponding block;
Means for calculating the total power of the conversion coefficient in the sideband and obtaining the received power measured in the sideband;
Where N is greater than 1 [25].
[27] The means for estimating the thermal noise comprises:
[25] The apparatus of [25], further comprising means for filtering received power measured in the sideband to obtain estimated thermal noise.
[28] means for measuring received power in the signal band;
Means for estimating total received power based on received power measured in the signal band;
Means for estimating an increase in heat (RoT) based on the estimated thermal noise and the estimated total received power;
The apparatus of [25], further comprising:
[29] The means for measuring the received power in the signal band is
Means for dividing the samples into blocks each containing N samples;
Means for transforming N samples of each block to obtain N transform coefficients of the corresponding block;
Means for calculating a total power of conversion coefficients in the signal band and obtaining received power measured in the signal band;
Where N is greater than 1 [28].
[30] means for estimating a load available to the cell based on the estimated RoT;
Means for performing scheduling and admission control based on the available load;
The apparatus of [28], further comprising:
[31] In a computer program product having a computer-readable medium,
The computer readable medium is
Code for causing at least one computer to measure received power in a sideband outside the signal band;
Code for causing the at least one computer to estimate thermal noise based on received power measured in the sideband;
Computer program product including.
[32] The computer-readable medium is:
Code for causing the at least one computer to divide samples into blocks, each block including N samples;
Code for causing the at least one computer to transform N samples of each block to obtain N transform coefficients of the corresponding block;
A code for causing the at least one computer to calculate a total power of conversion coefficients in the sideband and to obtain a received power measured in the sideband;
The computer program product of [31] above, wherein N is greater than 1.
[33] The computer readable medium comprises:
[31] The computer program product according to [31], further including code for causing the at least one computer to filter received power measured in the sideband to obtain estimated thermal noise.
[34] The computer-readable medium is:
Code for causing the at least one computer to measure received power in the signal band;
Code for causing the at least one computer to estimate total received power based on received power measured in the signal band;
Code for causing the at least one computer to estimate an increase in heat (RoT) based on the estimated thermal noise and the estimated total received power;
The computer program product according to [31], further including:
[35] The computer readable medium comprises:
Code for causing the at least one computer to divide samples into blocks, each block including N samples;
Code for causing the at least one computer to transform N samples of each block to obtain N transform coefficients of the corresponding block;
Code for causing the at least one computer to calculate the total power of the transform coefficients in the signal band to obtain the received power measured in the signal band;
The computer program product of [34] above, wherein N is greater than one.
[36] The computer-readable medium is:
Code for causing the at least one computer to estimate an available load for a cell based on the estimated RoT;
Code for causing the at least one computer to perform scheduling and admission control based on the available load;
The computer program product according to [34], further including:

Claims (35)

In a method for estimating thermal noise in a communication system,
Measuring the received power in the signal band;
And measuring the received power in the sideband outside of the signal band,
Estimating thermal noise based on received power measured in the sidebands ;
Based on the prior Symbol received power measured in the signal band, estimating a total received power,
By the processor, based on the received power measured during the sideband, viewed contains a estimating a thermal noise during the signal band,
The sideband includes guard subcarriers, and the signal band includes usable subcarriers among a plurality of subcarriers . Measuring the received power in the sidebands
Splitting the samples into blocks where each block contains N samples;
Transforming N samples of each block to obtain N transform coefficients of the corresponding block;
The method of claim 1, further comprising: calculating a total power of transform coefficients in the sideband to obtain a received power measured in the sideband, where N is greater than one. Method. Estimating the thermal noise is
The method of claim 1, comprising filtering received power measured in the sideband to obtain an estimated thermal noise. Estimating the thermal noise is
The method of claim 1, comprising filtering received power measured in the sideband with an infinite impulse response (IIR) filter to obtain estimated thermal noise. Estimating the thermal noise is
The method of claim 1, comprising averaging the received power measured in the sideband over a sliding window of a predetermined length to obtain an estimated thermal noise. Measuring the received power in the signal band is
Splitting the samples into blocks where each block contains N samples;
Transforming N samples of each block to obtain N transform coefficients of the corresponding block;
The method of claim 1, further comprising: calculating a total power of transform coefficients within the signal band to obtain a received power measured in the signal band, where N is greater than one. Measuring the received power in the signal band is
Filtering the N transform coefficients of each block with a matched filter to obtain N filtered coefficients of the corresponding block;
The method of claim 6, further comprising calculating a total power of filtered coefficients within the signal band to obtain a received power measured in the signal band. Estimating the total received power is:
The method of claim 1, comprising filtering received power measured in the signal band to obtain the estimated total received power. The method of claim 1, further comprising estimating an increase over heat (RoT) based on the estimated thermal noise and the estimated total received power. Estimating the RoT is
10. The method of claim 9 , comprising calculating the RoT based on the estimated thermal noise, the estimated total received power, the sideband, and an effective signal band for the total received power. Estimating the RoT is
The method of claim 10 , further comprising calculating the RoT based further on a selected calibration factor to provide a predetermined RoT value when no signal is applied. Estimating an available load for the cell based on the estimated RoT;
The method of claim 9 , further comprising performing scheduling and admission control based on the available load. Performing the scheduling and admission control includes
Selecting a user to admit or schedule;
Determining the load of the selected user;
13. The method of claim 12 , comprising updating the available load based on the selected user load. Amplifying the analog input signal to obtain an amplified signal having a thermal noise floor higher than the quantization noise of an analog to digital converter (ADC);
Digitizing the amplified signal with the ADC to obtain a sample;
The method of claim 1, further comprising measuring received power in the sideband based on the samples. The method of claim 9 , further comprising reporting the estimated thermal noise, the estimated RoT, or both to a network controller.   The method of claim 1, wherein a location of the sideband is selected based on frequency spacing between adjacent CDMA channels.   The method of claim 1, further comprising estimating an interference-over-thermal (IoT) based on the estimated thermal noise. In a device for wireless communication,
Measure the received power in the signal band,
Measuring the received power in the sideband outside of the signal band,
Based on the measured received power in the previous SL signal band, it estimates the total received power,
Comprising at least one processor for estimating thermal noise in the signal band based on received power measured in the sideband ;
The sideband includes guard subcarriers, and the signal band includes usable subcarriers among a plurality of subcarriers . The at least one processor comprises:
Divide samples into blocks where each block contains N samples,
Transform N samples for each block to obtain N transform coefficients for the corresponding block;
Calculate the total power of the conversion coefficient in the sideband to obtain the received power measured in the sideband;
19. The apparatus of claim 18, wherein N is greater than one. The at least one processor comprises:
The apparatus of claim 18, wherein received power measured in the sideband is filtered to obtain estimated thermal noise. The at least one processor comprises:
The apparatus of claim 18, wherein a rise against heat (RoT) is estimated based on the estimated thermal noise and the estimated total received power. The at least one processor comprises:
Divide samples into blocks where each block contains N samples,
Transform N samples for each block to obtain N transform coefficients for the corresponding block;
Calculating the total power of the transform coefficients in the signal band to obtain the received power measured in the signal band;
23. The apparatus of claim 21 , wherein N is greater than one. The at least one processor comprises:
Based on the estimated RoT, estimate the available load for the cell;
The apparatus of claim 21 , wherein scheduling and admission control are performed based on the available load. In the device
Means for measuring received power in the signal band;
It means for measuring the received power in the sideband outside of the signal band,
Based on the prior Symbol received power measured in the signal band, means for estimating the total received power,
Means for estimating thermal noise in the signal band based on received power measured in the sideband ,
The sideband includes guard subcarriers, and the signal band includes usable subcarriers among a plurality of subcarriers . The means for measuring the received power in the sideband is
Means for dividing the samples into blocks each containing N samples;
Means for transforming N samples of each block to obtain N transform coefficients of the corresponding block;
25. The apparatus of claim 24 , further comprising means for calculating a total power of transform coefficients in the sideband and obtaining received power measured in the sideband, wherein N is greater than one. . The means for estimating the thermal noise comprises:
25. The apparatus of claim 24 , comprising means for filtering received power measured in the sideband to obtain estimated thermal noise. Means for measuring the received power in the signal band,
Means for dividing the samples into blocks each containing N samples;
Means for transforming N samples of each block to obtain N transform coefficients of the corresponding block;
25. The apparatus of claim 24 , comprising means for calculating a total power of transform coefficients within the signal band to obtain a received power measured in the signal band, where N is greater than one. 25. The apparatus of claim 24, further comprising means for estimating a rise over heat (RoT) based on the estimated thermal noise and the estimated total received power. Means for estimating a load available to the cell based on the estimated RoT;
30. The apparatus of claim 28 , further comprising means for performing scheduling and admission control based on the available load. In a computer program stored in a computer-readable storage medium,
Code for causing at least one computer to measure received power in a signal band;
At least one computer, and code for the received power, is measured during a sideband outside of the signal band,
Before SL least one computer based on the received power measured in said signal band, code for causing the estimated total received power,
Wherein at least one computer, on the basis of the received power measured during the sideband, see contains the code for causing the estimated thermal noise during the signal band,
The computer program including the sideband includes guard subcarriers and the signal band includes usable subcarriers among a plurality of subcarriers . Code for causing the at least one computer to divide samples into blocks, each block including N samples;
Code for causing the at least one computer to transform N samples of each block to obtain N transform coefficients of the corresponding block;
Further comprising code for causing the at least one computer to calculate the total power of the transform coefficients in the sideband and to obtain the received power measured in the sideband. The computer program according to claim 30 , wherein the computer program is greater than one. 32. The computer program of claim 30 , further comprising code for causing the at least one computer to filter received power measured in the sideband to obtain estimated thermal noise. 31. The computer program of claim 30, further comprising code for causing the at least one computer to estimate an increase over heat (RoT) based on the estimated thermal noise and the estimated total received power. Code for causing the at least one computer to divide samples into blocks, each block including N samples;
Code for causing the at least one computer to transform N samples of each block to obtain N transform coefficients of the corresponding block;
Further comprising code for causing the at least one computer to calculate the total power of the transform coefficients in the signal band to obtain the received power measured in the signal band, where N is 1 34. The computer program of claim 33, wherein the computer program is large. Code for causing the at least one computer to estimate an available load for a cell based on the estimated RoT;
34. The computer program product of claim 33 , further comprising code for causing the at least one computer to perform scheduling and admission control based on the available load.

Images